With the growing interest in energy conservation, increasingly more machines, such as mobile industrial work machines or stationary power generation machines, are supplied with electric drive assemblies or systems for operating various tools or functions of the machine. Ongoing developments in electric drives have made it possible for electrically driven machines to effectively match or surpass the performance of mechanically driven machines while requiring significantly less fuel and overall energy. As electric drives become increasingly more commonplace with respect to such machines, the demand for more efficient generators and techniques for controlling same has also increased.
Among the various types of electrically driven machines available for use with such electric drives, switched reluctance (SR) machines have received great interest for being robust, cost-effective, and overall, more efficient. An SR machine is typically used to convert mechanical power received from a primary power source, such as a combustion engine, into electrical power for performing one or more operations of the machine. Additionally, an SR machine may be used to convert electrical power stored within a common bus or storage device into mechanical power. SR machines can similarly be used in conjunction with other generic power sources, such as batteries, fuel cells, and the like. Still further, SR machines can also be used with stationary machines having conventional power sources such as windmills, hydro-electric dams, or any other generic power source commonly used for stationary applications. While currently existing systems and methods for controlling SR machines may provide adequate control, there is still much room for improvement.
A typical SR machine essentially includes a multi-phase stator that is electrically coupled to an electric drive circuit, and a rotor that is rotatably positioned within the stator. In a motoring mode of operation, the electric drive selectively enables switches or gates associated with each phase of the stator so as to cause electromagnetic interactions between the stator and rotor poles and rotate the rotor relative to the stator at a desired torque and/or speed. Alternatively, in a generating mode of operation, the electric drive may be configured to receive any electrical power which may be induced by mechanical rotations of the rotor relative to the stator. The electric drive may use the electrical power that is induced during the generating mode to power auxiliary or accessory devices of the associated work machine, or in some cases, store the electrical power in an energy storage device.
Control of the SR machine, and thus, of the electric drive typically begins at a programmable microprocessor. More specifically, a microprocessor is preprogrammed with an algorithm which monitors various parameters of the machine and transmits different instructions to the electric drive for controlling the SR machine according to changes in the parameters detected. Such closed loop processes are executed at predefined rates that are essentially limited by the capabilities of the microprocessor and the manner by which the algorithm is implemented by the microprocessor. However, as the demand for more efficient and higher performance SR machines continues to grow, so does the demand for more efficient algorithm implementations and controllers with greater bandwidth.
Accordingly, there is a need to improve the performance capabilities and efficiency of an SR machine. Moreover, there is a need to improve overall control of electric drives, and thus, the manner by which SR machines are operated. More particularly, there is a need to improve upon the operating bandwidth of conventional controllers associated with SR machines.